Can picky protists help control an algal bloom?

Mixotrophic dinoflagellates (MTDs) are a major constituent of the microbial food web, but also play a huge role in the outbreak of red-tide events. Our understanding of the microbial mechanisms behind these red-tide outbreaks can be aided by studying top-down feeding on MTDs by their predators.


The growth rate and feeding preferences of Favella ehrenbergii, a Tintinnid ciliate, were studied by Yang et al. (2019) in both single and mixed prey conditions. Two MTDs; Scrippsiella trochoidea and Heterocapsa triquetra, were used as prey in the lab over 48hrs. No flashy, modern molecular techniques here- a seemingly well thought out methodology, microscopy work and mathematics enabled the estimation of growth rates, and subsequently prey preferences.


In short, Tintinnids achieve a higher growth rate when fed mixed diets compared to a monodiet and switch their feeding preferences to other species when mixed prey is available. This is likely due to their desire to consume fatty acids available from different MTDs and will undoubtedly affect the top-down control of MTDs.


Relevant to microbial trophic ecology, Yang and colleagues highlight an important link to potentially harmful red-tide events. Despite this, I do wonder how a small scale lab experiment can be applied to such a large scale phenomenon, making me think the authors’ claims that this research could help ‘predict’ red-tide outbreaks seems a bit far-fetched! No doubt though that this work will contribute to the understanding of red-tide MTD ecology and provide further knowledge of important microbial food webs.



Yang, J., Löder, M. G. J., Jiang, Y., & Wiltshire, K. H. (2019). Are tintinnids picky grazers: Feeding experiments on a mixture of mixotrophic dinoflagellates and implications for red tide dynamics. Marine pollution bulletin, 149, 110488.